It’s no secret that Ohio State’s offense has come out in 2013 firing for the end zone.

And the Buckeyes — whether it has been No. 1 quarterback Braxton Miller or backup Kenny Guiton — have been throwing touchdown passes at a school-record clip. With a combined 19 through five games, they are on pace to surpass the record of 33 set in 1995 by Bob Hoying (29), Stanley Jackson (two) and Tom Hoying (two).

“That vertical passing game, they’ve been not only effective, they’ve been deadly,” said Northwestern coach Pat Fitzgerald, whose Wildcats will play host to Ohio State on Saturday night. “That’s how they beat Wisconsin. They were just explosive. And you watch the Cal game and the way they were explosive, and really in all the games this year.

“It’s just really impressive to watch, and very similar to us, not just with one quarterback but with two. When Braxton went out, Kenny Guiton didn’t miss a beat. That’s a testament to those two young men, and to Coach (Urban) Meyer and his staff.”

Guiton already tore into the school-records envelope. He set a record with six touchdown passes in game, all in the first half, during a 76-0 victory over Florida A&M on Sept. 21. The previous record was five, with Bob Hoying doing it twice and John Borton once, in 1952.

Miller stepped back in last week to lead a 31-24 victory over Wisconsin, throwing four touchdown passes to tie a career high.

Miller and Guiton are a combined 99 of 144 passing with just three interceptions. That means they are averaging roughly one touchdown toss every five completions. Guiton has 13, Miller has six, and there still are seven games left in the regular season, with postseason statistics counting, too.

All of this on a team that a year ago this time was almost too scared to throw the ball, even as it put together an undefeated season. Meyer had called out his inexperienced receiving corps in the spring and during the season last year for not playing on an OSU-caliber level. And Miller said this week that at that time, he wasn’t close to where he needed to be in terms of throwing mechanics and reading defenses.

Both of those situations have changed dramatically.

“What’s that adage, necessity is the mother of invention?” offensive coordinator Tom Herman said. “You saw how defenses started playing us the end of last year (cheating up to stop the run). In order for us to be who want to be running the football, we had to make (the passing game) a viable threat.”

Four receivers have caught two touchdown passes each in at least one game this year. Corey Brown has done it twice, including last week, and Chris Fields, Evan Spencer and Devin Smith each have done it once.

And Miller has come a long way from a wing and a prayer.

“There’s just more confidence in the guys,” Miller said. “Last year, we didn’t really know how to run routes, and I really wasn’t comfortable with the playbook as much as I am right now.”

Take his favorite touchdown pass of last week, for example, a 40-yarder to Brown just one second before halftime to give OSU a 24-14 lead.

“I felt like it was going to be open, that’s why I looked to the right first (freezing the safety), then stepped into the pocket to the left,” Miller said. “That’s why (Brown) was so wide open, and I threw it in there.”

He said he probably couldn’t have pulled that off a year ago, just like the back-shoulder throw to Smith for one of the earlier scores against Wisconsin — Smith was his second read on that play.

“It’s just taking time with ball placement, and getting a lot of reps with the guys,” Miller said. “It helps a lot.”

His confidence is brimming, so much so he offered this about the game against the Wildcats.

“There’s a couple coverages they play, and we’ve got good plays for it,” Miller said. “Hopefully, we can take advantage of that.”